The present invention relates to a magnetic pin for concentrating and separating particles.
The latest detection methods for nucleic acids, such as polymerase chain reaction (PCR), ligase chain reaction (LCR), nucleic acid sequence based amplification (NASBA), strand displacement amplification (SDA), can be carried out by amplification of nucleic acids with extreme sensitivity. Because of this sensitivity the methods are very susceptible to contaminations. In this connection, the danger of contamination increases with the increasing number of steps and the manipulations to be made, such as centrifugation and pipetting steps. Thus, it should be important to the experimenters to keep the number of steps and manipulations as small as possible. However, this is often problematic, since differing sample volumes must be observed for differing steps and concentration of the sample volume is necessary in between. Therefore, there is a demand for a possibility of dispensing with manipulation steps, particularly centrifugation steps, in the above mentioned method, by taking the sample to be analyzed directly out of the various vessels, such as cups or microtiter trays, and transferring it. This demand of easily transferring samples from a large volume to a smaller volume and being able to easily change the sample containers, respectively, is, of course, not only limited to the field of nucleic acid technique but exists throughout (bio)chemistry where the concentration of samples is necessary.
Therefore, it is the object of the present invention to provide an apparatus by means of which target molecules can easily be taken out of the containers or vessels and transferred into other vessels so as to be able to dispense with manipulation steps, such as centrifugation steps, and work with small volumes.
This object is achieved by a magnetic pin according to claim 1. Advantageous embodiments follow from the subclaims.
In order to derive an advantage for the above mentioned methods by means of the magnetic pin according to the invention, magnetic labeling of the target molecules must, of course, be given. A person skilled in the art knows how to achieve this. For example, this is achieved in that the target molecules as such have magnetic properties or are bound to xe2x80x9cmagnetic beadsxe2x80x9d. If a detection method is concerned, another possibility is to link streptavidin to iron so as to bind the target molecules which in turn are labeled with biotin.
In an exemplary method in which the magnetic pin according to the invention is used, the sample material, e.g. serum, plasma, whole blood, cells or tissue, is subjected to a chemical or chemico-enzymatic breaking-up and a denaturation, respectively. This solution simultaneously contains a first nucleic acid oligonucleotide (primer) which hybridizes as a probe to the target molecules. This oligonucleotide is covalently bonded to a biotin molecule which can be bound by streptavidin with high affinity. This streptavidin in turn is bound to particles which contain iron. Because the streptavidin particles cannot be added to a denatured sample mixture, since otherwise they would denature as well and would lose their bonding properties to biotin, the sample mixture must be diluted, which increases the sample volume. However, this great sample volume has a negative effect on subsequent steps, such as amplifications. For example, the resulting conjugates (samplexe2x80x94oligonucleotidexe2x80x94biotinxe2x80x94streptavidinxe2x80x94iron) are transferred by means of the magnetic pin according to the invention into another container where the further steps can then take place in a much smaller volume.